Conventionally, there have been used many image forming apparatuses employing the electrophotographic method as an image forming apparatus such as a copier or a printer.
The image forming apparatus employing the electrophotographic method forms an electrostatic latent image on the surface of a photoreceptor (toner image carrier). The image forming apparatus then develops the electrostatic latent image with toner supplied from a developing device, and transfers and fixes a toner image thus developed to a recording medium such as a sheet.
In recent years, a two-component developer excellent in toner charging stability has been used as a developer for the purpose of obtaining color images and high quality images. The two-component developer is composed of toner and a carrier, which are stirred in a developing device so that the toner and the carrier are rubbed against each other, and properly charged toner is obtained by the friction.
In such a two-component developer, since toner is consumed in every developing processing, a developing device is provided with a toner cartridge (which is also referred to as a toner supplying device) supplying (replenishing) toner into the developing device depending on a toner consumption amount.
As a toner cartridge, for example, a toner cartridge disclosed in Japanese Laid-Open Patent Publication No. 2008-281868 is known that is provided with a toner storage container that stores toner, a toner discharge roller that discharges toner, and a toner scooping member (stirring vane) that scoops up toner toward the toner discharge roller.
However, there is a casein the toner cartridge disclosed in Japanese Laid-Open Patent Publication No. 2008-281868 that when a toner amount remaining in the toner cartridge is large, if a sheet of the toner scooping member is thickened for increasing stiffness in order to scoop up the toner reliably, a toner stirring torque becomes so large that an unnecessary pressure (stress) is imposed on the toner to deteriorate the toner, resulting that fluidity of the toner is lowered. There is also a case that when a toner amount remaining in the toner cartridge decreases, the toner amount remaining scooped up by the toner scooping member becomes small so that a toner supply amount is reduced.